jdegoes

Applied Functional Programming with Scala - Notes

Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

jamesmfriedman

# -*- coding: utf-8 -*-

import datetime
from south.db import db
from south.v2 import SchemaMigration
from django.db import models
from django.db.models import get_app, get_models


class Migration(SchemaMigration):

dionyziz

A pseudonymous trust system for a decentralized anonymous marketplace

Dionysis Zindros, National Technical University of Athens dionyziz@gmail.com

Keywords

pseudonymous anonymous web-of-trust identity trust bitcoin namecoin proof-of-burn timelock decentralized anonymous marketplace openbazaar

Abstract

hdgarrood

Haskell projects with lots of dependencies on Travis CI

If your Haskell project has lots of dependencies, you can find yourself reaching the timeout while compiling them - the free service has a timeout of 50 minutes. How do we address this?

First, a quick reminder of build statuses in Travis CI:

All builds finish with one of four possible statuses: succeeded, failed, errored, or (manually) cancelled. The difference between a failed and errored

TomasMikula

import scala.language.implicitConversions

object Lazy {

  def lazily[A](f: => A): Lazy[A] = new Lazy(f)

  implicit def evalLazy[A](l: Lazy[A]): A = l()

}

chris-martin

Step one

curl https://nixos.org/nix/install | sh

Step two

Add the following lines to the end of ~/.zshrc:

source $HOME/.nix-profile/etc/profile.d/nix.sh

5outh

{-# LANGUAGE OverloadedStrings #-}

module Main where

import Control.Monad.State
import Data.Text
import Data.Monoid
import qualified Data.Map as M
import Control.Monad

chris-martin

@aredridel

Thought of the moment: I never use === in javascript. I find that every time I need it, I've made a boneheaded design flaw elsewhere.

‏@chris__martin

@aredridel === is a promise to the maintainer who comes after you that you knew what you were doing.

‏@aredridel

ryanlecompte

// Usage examples:
val a = Vector(1,2,3).zipMany(Vector(1,2,3), Vector(5,6,7), Vector(8,9,10), Vector(11,12,13))
Vector(Vector(1, 1, 5, 8, 11), Vector(2, 2, 6, 9, 12), Vector(3, 3, 7, 10, 13))

a.unzipMany
Vector(Vector(1, 2, 3), Vector(1, 2, 3), Vector(5, 6, 7), Vector(8, 9, 10), Vector(11, 12, 13))

// Implementation
import scala.collection._
import scala.collection.generic.CanBuildFrom

persson

#!/bin/sh

#Yes, there is no six
hosts=(pipe1 pipe2 pipe3 pipe4 pipe5 pipe7 pipe8 pipe9)
names=(pipe1 pipe2 pipe3 pipe4 pipe5 pipe7 pipe8 pipe9)
sessions=(1 2 3 4 5 7 8 9)

tmux new-session -d -s pipelines

i=0